Thermostatic steam trap



July 4, 1950 H. L. JOHNSON THERMOSTATIC STEAM TRAP Filed June 15, 1945Ham/d L Job/7500 B) H/SA 7'TORNEYS Patented July 4, 1950 UNITED STATESPATENT OFFI CE THERMOSTATIC STEAM TRAP Harold L. Johnson, Wilkes-Barre,Pa., assignor to W. H. Nicholson & Company, Wilkes-Barre, Pa., acorporation of Pennsylvania Application June 15, 1945, Serial No.599,579 2 Claims. 01 236-56) This invention relates to thermostaticallycontrolled steam traps. It is an object of the invention to provide animproved trap of the thermostatic type suitable for draining apparatussupplied with steam under high pressure and temperature. In traps of thetype described, the thermal unit, unless protected, would be subjectedto erosion caused by the impact of high velocity steam, water, particlesof dirt, scale and other foreign matter striking directly against thethermal unit. Therefore it is another object of this invention toprovide in a trap of the type described means to protect the thermalunit from erosion by impact of scale, dirt, or high velocity steam orwater there against. Other objects. and advantages of this inventionwillappear as it is described in connection with, the accompanyin drawing.

In the drawing: v

Fig. 1 is a vertical sectional view of a steam trap in accordance withthis invention;

Fig. 2 is a fragmentary vertical sectional view of a modifiedconstruction;

Fig. 3 is a view in elevation, looking from the right of the inletreducing connection shown in section in Fig. 2; and

Figs. 4 and 5 are a view in elevation and a partial view in elevation,respectively of modified constructions of the means for protecting thethermal unit.

A steam trap in accordance with this invention comprises a casing orbody I of conventional form, having an inlet opening 2 adapted to beconnected to the apparatus to be drained, and an outlet opening 3suitable for connection to a discharge or drain pipe. Thetop of .thecasing l is closed by a cover or cap 4 to which the thermal unit 5 isattached. The thermal unit 5 may be fabricated and charged withtemperature-responsive fluid by any of several methods known to themanufacturers of such devices, and inits usual form consists of aconvoluted bellows 5a and closing elements 6 at the top and 1 at thebottom, suitably fastened together to form a leakproof envelope orcontainer, such as bysoldering, brazing or welding. The top closingelement 6 is provided with a threaded stud 8 for fastening the thermalunit tothe cover 4, and the bottom closing element 1 has a centrallypositioned threaded opening 9 for receivingthe stem of a valve In.

Directly beneath the valve ID and in alignment with the coinciding axisof the valve In and the thermal unit 5 is a valve seat H threaded in anopening in the casing I leading to the outlet open 2 ing 3, and providedwith a flange l2 of suitable size and shape to permit installation andremoval of the valve seat with standard sockettype wrenches.

Surrounding the thermal unit 5 is a cylindrical shield l3 which extendssubstantially the entire length of the thermal unit, and which isprovided at the lower end portion with an inwardly curved flange M whichis seated between the flange l2 of valve seat II and a raised boss I 5in the casing I- The shield I3 is thus centered, fastened and maintainedin correct position'by the valve seat I I. The shield I3 extends upwardinto the cover 4 a sufficient distance to permit only a smallcircumferential opening [6 between the shield and cover, this openingbeing of suflicient area to allow the incoming steam easy access to thethermal unit 5, without directly. impinging against the convolutedbellows of this unit, but small enough to exclude dirt, scale andforeign matter of sizes large enough to damage these convolutions.

In the lower end of the shield l3 are located one or more openings llfor permitting the condensate which enters the casing I through inlet 2to bedischarged through the orifice [8 of valve seat H, and thence tooutlet 3. The openings I! are preferably horizontal to avoid directimpingement of the condensate against the thermal unit, and placed lowenough in the shield l3, with relation to the valve seat II and inlet 2,so substantially all of the condensate will flow to the outlet 3 by theforce of gravity, from the trap, the apparatus it drains and theconnecting piping, when the steam supply is shut off. By thus preventingthe collection of pockets of water in said apparatus and piping,freezing and its consequent damage is avoided on applications subjectedto-low temperature.

The combined total area through the openings I'lis madeto apredetermined lesser area than the orifice l8 through valve seat I I,thereby permitting condensate to be discharged through orifice 18 at afaster rate than it can enter the space I9 formed by the shield I3around the thermal unit 5, thereby obviating collapse of the thermalunit from contact with a considerable volume of water traveling at highvelocity, a condition commonly called water-hammer. The openings 11 aremade small enough to exclude from the space I9 dirt, scale, pieces ofpipe and gasket of sufficient size to damage the convolutions of thethermal unit 5, or which might lodge between the valve I0 and valve seatll, causing the trap to become inoperative.

sion. The topand .bottom closingxelements' 6 Where it is desirable tomaintain a greater volume of condensate in the casing I for moreintermittent trap operation and the danger of freezing is not aconsideration the openings 17 may be omitted and the shield be formedwith a solid wall as at 45 in Fig. 4 and where it is desirable to screensmall particles of dirt, scale, etc. from the condensate the shield maybe formed as in Fig. 5'where the wall llis provided with a plurality ofsmall openings 48 extending upwardly in the wall 41 sufiiciently toprovide the desired area of opening-and with the Openings small enoughto screen out all particles over a permissible size.

To aid in preventing collapse or-the thermal unit 5 from the efiects ofwater-hammer a, wall or partition is integrally formed with thecasing lbetween the interior of this casing and the inlet 2. An opening 2|through this partition of a predetermined lesser area than the orificel8 through the valve seat H permits condensat to be discharged throughorifice l8 at a -faster rate thanit can enter-the interior ofcasing Ithrough the opening 2!. The opening 2lis preferably placed. low enough.in partition 29, with relation to the inlet'2 and .valve seat ,so all-ofthe condensate can fiowto'the outlet 3 by'the force of gravity, :fromthe apparatus drained and the connectingspiping, when: the steam supplyis shut off. .By thus preventing the collectionof pockets of waterinnsaidrapparatus and piping, freezing and its consequentfdamage isavoided onth'ose applicationsasubjected to low temperature.

Wherethe casing [is not-provided with an integral wall,aas the Wall 2fiof Fig. 1, there may be provided in the inlet [an inlet reducing.connection as the removable fitting :22 shown in Figs 2 and 3.TherfittingiZZ has athreaded end portion :23 adapted to be engaged inthetrap inlet'fi aand. its opposite end 'Of suitable-- shape forengagement with .a wrench a1'i'd-"formedwith a threaded opening 24 forconnection to theapparatus 'to be drained. Theopening i25 through theend123 .preferablyawill have a lesser area than the orifice l8lthroughthe'valve seat "I I, thus permitting condensate to bedischargedthrough the orifice 8 at a faster rate than. it can entertheinterior of easing l'through theopening 25. The top closing element-6of thermal unit 'iis provided with an inwardly extending hollowcylindrical tubetZfi integral therewith-rand the-bottom closing element1 is provided with an inwardly extending integral cylindrical stem 21.These parts are machined so stem 12! is av close sliding fitlinside thehollow tubeZB. A shoulder 28 is included on .stem 121.against'swhichthevend of hollow .tu-bel26 abuts when thethermalunit-5 iscontracted,'thus limiting the contractionof the thermal unit to apredetermined minimumdimenand l are manufactured and the thermal runitfiis; assembled so that threaded stud'8, hollow tube 26, threaded Opening:9 and cylindrical stemi'! are in alignment axially'at all pointsbetween the extreme extended and contracted positions ofithe thermalunit. This vconstruction.prevents fl'exural distortion of the thermalconvolutions and insures proper seating '01 the valvetil in'valve'sseat' I I when thermal unit: 5"is extended during operation.Openings?!) in'the hollow tube 1 2.5 and openings 30 in cylindrical stem21 r. are

"element 6 and the bottom closing element 1 are p10VidGd' i\Vith"fi&tshoulders or steps 42 formed dimensionally parallel to fit standard fiatwrenches.

While the invention has been shown and described in connection with athermal unit of a particular'zcons'truotion it is to be understood theinvention. is equally applicable to thermal units of other types andconstructions Where protection of the unit is desirable.

Whatis claimedis: I

'1. line thermostatic steam trap, acas-ing having inlet and*dis'c'harg'e openings, a thermal unit mounted in-said "casingya valveoperated by said thermalpnit-and controllingsaid discharge opening,guide means' within said thermal unit rigid with saidcasingp'guide'meanscooperating with saidrigid-guide"means'andmoving with the thermal unitto guide said" valve, a seat for said valve mounted in said "d-ischarge'open-ing, and shieldi-ng -mea'ns forsai-d thermal unit comprisinga metallic cup-shaped member surrounding said thermalunit andhaving itsbase portion secured to saidcasing'by -saidvalve'--seat, the side wallof --said cup-shaped member being imperforate around said "thermal unitand having drainage holes in the zone adjacent said valve seat.

2. In a thermostatic steam trap, a casing hav ing inlet and dischargeopeningaa thermal unit mounted in saidca'sing, 'a valve' operated bysaid thermal u-nitand controlling said discharge opening, guid'e=-meanswithin said thermal unit rigid with said casing, guid'ameahs cooperatingwith said i' ig i'd gtiidemeans ari'd moving with'thethermalunit'toguide said valve; a seat for said valve mounted in said dischargeopening, shielding means for said thermal 'unit i'mmovably secured tosaid casing by -said" valve 's'eat and' restricting the fiowofflriid tosaid discharge opening said shielding means having a side wall "formedand positioned "to prevent impingement against said thermal unit of dirtparticles.

HAROLD L. JOHNSON.

REFERENCE-S" CITED The"following'references"are of record in the file ofthis-patent:

llNITED. s'rA'rEs PATENTS lGreatvBritain Mar. 23, 1938

